Lubricant



Patented Mar. 4, 947

N "OFFICES I Franklin M. Watkins, Chicago, Ill., assignor to Sinclair Refining Company, New York,

corporation of Maine No Drawing. Application December 31,1943,

Serial No. 516,525

This invention relates to lubricating oil compositions and more particularly to lubricating oil compositions consisting principally of a petroleum lubricating oil fraction and having improved characteristics, especially with 'respectto oxidation and corrosion, by reason of the incorporation treme pressure characteristics of a lubricant may be improved by the addition thereto of relatively large proportions of polymerized aliphatic nitriles prepared-by heating an aliphatic nitrile in the presence of a polymerizing agent such as metal chlorides, chlorides of phosphorus and sulfur, phosphorus pentasulfide, elemental phosphorus or sulfur. It has been suggested that such polymerized aliphatic nitriles maybe used alone as extreme pressure lubricants or. that vthey may be added to ordinary mineral oil lubricants, and greases to impart extreme pressure lubricating characteristics to such mineral lubricants.

The lubricating oil composition of ,my present invention is not to be confused with such extreme 5;;

pressure lubricants consisting of polymerized aliphatic nitriles or. mixtures thereof with other lubricants. i

I am at present unable definitely to identify,

by chemical formula, my improved lubricating oil addends. However, they; definitely appear to consist primarily ofchemically combined stearonitrile, phosphorus, and sulfur,- as distinguished from aapolymer of stearonitrile containing little or no phosphorus or sulfur. This, fact is apparent from the following observation;

, a. A maximum of 2 molesof the stearonitrile :reacts with each mole of phosphorus sulfide, for

instance P285. This hasbeen shown by the removal of excess nitrile by low pressure distillation after, a reasonable reaction period. b. Excess nitrile is not substantially polymerized'under the reaction conditions described here- .in, since excess nitrile maybe recovered from the 1'- act .l n itrm xt r s llat on in the or gina boiling range of the stearonitrile.

6 Claims. 01. 252-4217) These stearonitrile-phosphorus sulfide reaction products may be prepared by heating a mixture of the stearonitrile and. phosphorus sulfide, ad1- vantageously to a temperature of about 300f F., until a homogeneous mixture is obtained.

The time required for thecompletion of the reacL-;

tion is largely dependent upon the reaction tern;- perature employed. For instance, using a reaction temperature of 150-F., completion of the reaction may require say. 22 hours, while using a reaction temperature of 300 F., the reaction may-be completed in say 1 to 6 hours.

The proportion of stearonitrile and phosphorus sulfide used may be varied somewhat; howeveni-a molecular proportion of the'nitrile and-phosphorus sulfide of about 11 /2 has been usedwith advantage; It is desirable that substantially all of the stearonitrile be reacted with the phosphorus sulfide and as previously noted a maximum of *2 moles of the stearonitrile will react with 1 mole of the phosphorus sulfide. Any substantial ex,- cess of the stearonitrile is not desirable.

The reaction product of stearonitrile withpany one of the phosphorus sulfides previously noted have been found to be oil soluble and, when com.- pounded with lubricatingoil fractions, substantiallyto, inhibit corrosion of the bearing ,metal" in contact with theoil and materially to stabilize the oil composition 7 against deterioration. l'gur ether these stearonitrilephosphorus sulfide re'action products have been found to be particularly effective deactivatorSpf various metals, alloys, and metal compounds known to, accelerate the deterioration of the oil. Forinstance, it has previously been recognized that oxidation of many lubricatingoil compositions is materially accel erated'by contact with certain bearing metals or l o s, n ab y, opp all y i alsqa co nized' h t the ncel va iou metal o organicsubstances, includedin the oil composifor example, is knownmaterially to catalyze oxidation of the oil. Also, various metal compounds,

notably calcium organic compounds, for instance the calcium salt of octyl-salicylates, usedin lubricating oil compositions as detergents and oxidation inhibitors, have been found actually to effect an increase over the normal rate of corrosion of copper-lead bearing alloys by the lubricant and the normal rate of oxidation of the lubricating oil composition at the termination of the induction period. H

I-have discovered thatthe corrosion and oxidation characteristics of petroleum lubricating oil fractions either alone or compounded with various other addends, and even in the presence of prooxidant metals, may be substantially improved by incorporating therewith a minor proportion of one of these stearonitrilQphosphorussulfide reaction products."

These.stearonitrile-phosphorus sulfide reaction products have been found to be compatible with other desirable lubricating oil addends. and, the.

inclusion of such other addends, especially addends of the type used as detergenhis Within thi contemplation of my present 'inventi'onandconstitutes an important aspect thereof. The inclusion of said so-called detergenta for instance in internal combustion engine lubricants,

been found highly advantageous. An especially effective lubricating oil composition contemplated by my present invention is one comprising, in addition to the lubricating oil constituent and product, aminor proportion .of' 'the calcium salt of an octyl salicylate, particularly iso-octyl salicylate or capryl 'salicylate; These calcium salts 1944, and April 25, 1944; each1on an application .pliorus -sulfide reaction products and: other known detergents, for example-such as, calcium cetyl 'phenolate, phenolates of tertiary amyl phenol sulfide, barium phenolate of 'diamyl phenol su fide, metal sulfonates, soaps, especially basic soapshighly basic, calcium detergentsand'various other-known detergents of these general 3- types. 7 l I When used in conjunctionwith these detergents, particularly the calcium compounds such as'previ'ously mentionedjthese stea-ronitrilephosphorus sulfide reaction products' andthe deter- ,v gents have been found to complement each other so that-the effectivenessof each is promoted. The tendency of the detergent to "promote" oxidation ofQthe oiland corrosion of bearing metal at the termination of the oxidation induction period is minimized by the presence of said'reactio'n products'without destroying theefiec'tiveness of'eithejr the detergent or my new inhibitors.

'Mynew' type of inhibitor' r'nay be prepared-as V 104 grams (0.3 mole) of P457.

previously noted by. reacting stearonitrile with.

either phosphoruspentasulfide, phosphorus heptasulfide, or phosphorus trisulfid'e. The reaction products of -lauronitrile' -with" these phosphorus sulfidesh'ave' been 'fcundi'to have low oil solubility,-- However the reaction products of stearo- I A ily soluble-in such oils at room temperature over a range at least as'high as 1%, based on the weight of the oil. Stearonitriles prepared from double pressed stearic acid, containing about 50% stearic acid and;50% palmitic acid,'have been found satisfactory for use in the preparation of my improved addends.

Th stearonitrile-phosphorus sulfide reaction products used as an addition agent in the compounding of my improved lubricating oil composition may be prepared as presently described. For convenient subsequent reference, the reaction products and the method used in preparing the same will be designated A, B, C, and D respectively.

Inhibitor A This reaction product was prepared by reacting phosphoruspentasulfide, (P255) with a steamnitrile, prepared from double pressed stearic acid containing approximately equal. proportions of stearonitrile and palmitonitrile, having an average molecular weight of 251.

One mole of the nitrile and 100. grams of P2S5 (0.475 mole) were charged to a reactor equipped with a stirrer, thermometer and heater. The stirrer was started, the mixture slowly heated to 300 F. and held at -that temperature for 1 hour. During this heating the mixture slowly turned to deep red color and became homogeneous at 300 F. Upon cooling to room temperature, this red liquid thickened to the consistency of a thick syrup. Naphtha Wasthen added to reduce the viscosity of the mixtureandthe solut o Wa fil ered throu h a filtc aid -to remove any unreacted P285.- The filtrate was then topped to remova he added naphtha. By-this ope ation a yi ld of 2.16 grams of the. reaction prcduct w s obtai d h ving an a i nu be of 1 7 and contain n 7.76% ph sphorus and 20% sulfur.

, nhib tors This pr duct was p pa d by the method o the preceding example except that 251 grams '(1 mole) of the stearonitrile was heated with 0.58

mole of P 8 and the temperature Was hld at 300 F. for 6 hours. The resulting product was found to have an acid number of 283.5 and to c ntain 81 p o ph rus, 20.95% sulfur. and 29 nitr ns 7 Inhibitor c v The reactor used in the preceding examples was charged with 125.5 grams of the stearonitrileand I I I The mixture was stirred'and heated to a temperature of 300 F. for 1%! hours. The mixture was then cooled to 200 F. and filtered while hot through a bed of filter aid to emo e any cxcess or unreacted pho phorus sulfide. The filtrate was a, hick dark red liquid hav n an acid number of 13.1.4, a sapcn fic ti n n mber of 256.2 and containing 8.3 phosphorus, 15.6% sulfur, and'3.47% nitrogen.

Inhibitor .D

In the preparationjof this inhibitor, the reactor previously used was charged with 251 grams (1 mole) of the stearonitrile and 65 grams (0.412 mole) of P263 was added. The stirrer was started and the mixture heated for 1 hour at a temperature of 300 F. Themixture was then cooled to 200 F. and filtered through a filter aid. The product was a clear, dark red, viscous liquid having an acid number of 17.2, a saponification number of 157.8 and containing 4.88% phosphorus and 10. 5 sulfur.

The reaction products of stearonitrile with these phosphorus sulfides are very active chemically. They react readily with water, amines, alcohols, metallic oxides, and the like. The materials themselves appear to be stable at 400 F.

That they contain more than one typeof' reaction product is indicated by the fact that about 80% o'f'the phosphorus" present may be readily removed by'boiling with caustic, while the remainder of the phosphorus withstands long periods of digestion. Purification of the product is diflicult because of its viscosity andv its chemically very active characteristics. V

The characteristics f the lubricating oil constituent determined by conventional laboratory tests are very little affected by these inhibitors; This is illustrated by the following Table I in which there are set forth, in the first column, the characteristics of a solvent treated SAE 10 Mid-Continent base oil. In the second column there appear the characteristics of this base oil having incorporated therewith 0.1% of the reaction product previously designated Inhibitor A. In the third column there are set forth the characteristics of this base oil having incorporated therewith .1% of the previously referred to calcium salt of isooctyl' salicylate, but containing none of my present addends. In the'fourth column, there are set forth the characteristics of the base oil having incorporated L therewith 0.75% of the calcium iso-octyl salicylate' and 0.25% of the reaction product previously designated Inhibitor B. In each instance the percentages given are based on the weight of the oil constituent.

Table I 29. 3 29. 4 4 4 415 420 Fire, F"... r. 480 480 Viscosity, 100 F., S. U 249.6 251. 8 258. 5 252. 8 Viscosity, 210 F., S. U. S 49. 0 40.2 49. 5 49. 5 Viscosity index 92. 7 94 93. 3 97.8 Pour, "F 5 '5 5 q Carbon residue .039 04 331 20 Carbon residue (ash ire 039 04 163 .08 Ash 0.0 .0 168 .17 Acid. No 025 075 2. 3 '0. 4 Sap No lb .28 Color, P 2- 3+ 2% 3+ Stability, 45 at 350 4+ 4+ 3%+ 3%- Suifur, per cent .20 20 Calcium, per cent 084 048 Phosphorus, per cent 0L3 024 In the third-and fourth columns of the foregoing .tabulation, opposite acid No., the values are basic, due to the presence of the calcium salt.

f 'As' the lubricating oil constituent of my improved lubricating oil composition, various lubri- 'cating oil fractions may be used. For instance, solvent treated Mid-Continent neutral such as described in the foregoing tabulation or a blend of 'such neutrals withbright stock or a solvent refined lubricatingoil fraction from a Pennsyl-v yaniacrude or various blends of such lubricating oil fractions maybe employed. a

' The proportion of the stearonitrile-phosphorus sulfide reaction products used in the compounding of my improved lubricating oil composition may be varied somewhat, but in any 'case only alminor proportion is used. Concentrations as low as 0.05%, by weight, may frequently befused with advantage, particularlywhere no {metal salt detergent ispresent. Concentrations of about 0.5% have been found frequently to be desirable. The optimum concentration depends to a considerable extent upon thenature of the mineral oil constituent and the nature and amount of the detergent or other addends present. It is generally recognized that phosphorus acidity has a. tendency to promote sludge formation. By the p'roper'proportioning of my addend and a calcium salt detergent in the; lubricating oil composition of my presentinvention, thephosphorus set forth in the following TableII.

acidity, due to the presence of the inhibitor}. is neutralized thereby avoiding the sludge-forming tendency of the phosphorus. Where too little inhibitor is used, corrosionmay occur. Where too much inhibitor isused, objectionable phosphorus acidity-may result in the .absence of a neutralizing detergent or may not be completely neutralized if the proportion of the detergent used is insufficient. Wh'ere'the calcium salt of iso-octyl'salicylate, for instance, is used as a detergent, satisfactory results havebeen obtained where the calcium salt detergent and the inhibitor were used in proportions ranging from 2 to 10 parts of the calcium salt to 1 part of the inhibitor. Optimum ratios where other detergents are used may be readily determined experimentally. In the absence of a detergent, it is usually preferred to use not in excess of about 0.2% of the phosphorus-containing addend Where sludgingis particularly objectionable.

My inhibitors have been found to increase the oxidation induction period of calcium iso-octyl salicylate, for instance, and to maintain a low rate of oxygen absorption both with and withoutthe presence of copper-lead bearing metal.

In some instances, the inhibitor has been found completely to eliminate the induction period, 1. e.,

completely to deactivate the calcium of the detergent, and to maintain a low rate of oxygen absorption throughout. the conventional oxygen absorption tests, thus avoiding the high'rate of oxidation which normally occursfollowing the induction period. L V

The results of oxygenabsorptlontests carried out at 360 F. show that my. new class of inhibitors are strong metal-.deactivatorsand efficient anti-oxidants. Forexample, by. the addition of 0.15% of my inhibitor previously identified as A,

the oxygen absorption rate of the previously identified solvent treated Mid-Continent SAE base 10 oil was reduced from 2.8 cc. per minute per grams of oil to 2.2 cc. per minute. The addition of 0.5% of inhibitor D to the same base oil reduced the oxygen absorption rate to 1.25 cc. per minute In the presence of copper-lead bearing metal, and also in the presence of 0.01% of F8203, in the form of an oil soluble ironnaphthenate, recognized to be strong pro-oxidants, these pro-oxidant metals were found to be deactivated by small proportions of my inhibitors.

The result-s of oxygen absorption and corrosion tests, carried out at 360 F., of the previously described solvent treated Mid-Continent base oil and of blends of the base oil with the indicated proportions of my inhibitors previously identified, 'inth presence of recognized pro-oxidants, are

, Table II Oxygen In presence of absotrptlon (Bu-Pb bearing ra em Y Inhibitor presence of k .iron; O -absorp. Bearing naphthenate rate corrosion loss Cc./1riin. Mgs. 9

2.8 None 3. 6 None uteper 100 grams of the lubricant;

A- blend of the previously identified base oil with 1% of the calcium iso-octyl salicylatehad, in the absence of copper-dead bearing metal, an inductionperiod of 170 minutes and during said induction-period the oxygen absorption rate of the blend was 1.5 cc. per minute. By the addition of 0.15% of my inhibitor A to this blend, the

oxidation induction period Was increased to minutes, during which period the oxygen absorption rate was 1.07 cc. per minute. By the addition of 0.5% of my inhibitor A to the blend, the oxidation induction period. was entirely eliminated, and, though the average oxygen absorption rate throughout the test was slightly in eX- cess of the rate preceding the termination of the induction period of the blend alone, the marked increase of the oxygen absorption rate following the termination 'of the; induction period was avoided by the presence of my inhibitor. Where 0.5% of my inhibitor was added to this blend, the oxidation induction period was eliminated and the average oxygen absorption. rate throughout the test was only 0.9 cc. per minute. Where 0.5% of my inhibitor D was added to the blend, the induction period was extended to 388 minutes, during which period the oxygen absorption rate was 0.9 cc. per minute.

In the presence of copper-lead bearing metal, a blend of the previously identified base oils and 1% of the calcium iso-octyl salicylate had an oxidation induction period of 107 minutes, during which period the oxygen absorption rate was 2.1 cc. per minute. The copper-lead bearing corrosion loss during the test was 11 mgs. By the addition of 0.5% of my inhibitor A to this blend, the induction period was eliminated and, though the average oxygen absorption rate throughout the test was slightly in excess of that of the uninhibited blend prior to the termination of the induction period, the marked increase in the oxygen absorption rate at'the termination of the induction period, due to the activity of the detergent, was avoided.

By the addition of 0.5% of my inhibitor 0 to the blend of the base oiland the detergent, the l induction period even in the presence of copper.- lead bearing metal was eliminated. The average oxygen absorption rate throughout thetest was only 1.1 cc. per minute and no bearing corrosion loss was experienced. By the addition of 0.5% of my inhibitor D to this blend, the oxidation induction period was increased to 205 minutes and throughout this period the mean oxygen ab- I at 45 hour inte'rvals to ascertain the rate of oil deterioration, bearing corrosion and carbon and present instance, these tests were carried out on the previously identified solvent treated Mid- Continent SAE base oil alone, on said base oil having incorporated therein varying proportions of my inhibitor A, on a blerid of said base oil having incorporated therein 1% cities calcium salt of-iso-octyl salicylate (CIOS) and on blends of the base oil containing various proportions oi, the detergent and of my inhibitor B, The results of these tests, including characteristics of the 111-. bricant before and after the test; duration of test and the amount of sludge deposit and bearing corrosion loss, together with the identity'of the lacquer deposit-s in the test apparatus.- In the lubricant tested, are set forth in the followin table.

7 Table III Inhibitor type None A A None B B Inhibitor, percent None .05 0.10 None 0.15 0.25 OIOS, per cent None None None 1. 0 0. 75 ,075 Tests on fresh lubricant: Vis. at 210 F.S. U. S 49. 0 49. 2 49. 2 49. 5 49. 3 49. 5 Neutralization N o 0.025 .0. 05 0. 075 2. 3 0. 9' 0. 4 Results at termination of 7 test:

Duration of test, hrs 180 180 180 135 .135 VlS.8.l2 210 F.-S. U. S; 113. 0 59. 0 54. 3. 80. 2 5l. 0 52. 4 Neutralization No 9. 2 4. 0 1. 4 11. 5 0. 8 0. 6 Sludge on roof, gms... 17. 7 6. 2 2. 4 l1. 1 0. 9 10.3 Gu-Pb bearing loss,

rugs 300 14 8 906 None None In the foregoing tabulation the neutralization number is expressed as milligrams of potassium hydroxide per gram of oil required to neutralize the oil, excepting the neutralization number of the fresh samples containing the detergent,,which were basic. The tests of the sample of the third column was continued to 225 hours with little change in the results. Similarly the testof the sample of the fifth column was continued to 27.0 hours with little change in results. In each instance, the area of copper-lead bearing metal exposed to the oil Was 26.81 sq. cm.

The results of these tests show that the members of my new class of inhibitors are very active stabilizers against deterioration, as appears from the neutralization numbers, viscosity changes, sludge deposits and bearing corrosion losses under the accelerated oxidizing conditions of the test.

Since my new class of inhibitors are readily oil-soluble, they may be incorporated in the oil.

principally of a petroleum lubricatingoil fraction and containing in solution in said oil from about 0.05 to about 1%, by weight, of the -reac-'- tion product of stearonitrile and phosphorus P283; and

sulfide of the group consisting'of P285, P is-z. V g V 2. A lubricating oil composition consisting principally of a petroleum lubricating oil fraction and containing about 1% of the calcium salt of an octyl salicylate and about 0.05 to about'0.5% of the reaction product of stearonitrile and a phos phorus sulfide of the group consisting of P285, P283 and P is'l. V

3. A lubricating oil composition consisting prin- V cipally of a petroleum lubricating oilQfraction, and containing in solutionthe reactionproduct of stearonitrile and a phosphorus sulfide of the group consisting of P2S5,'P 2 S3 and P4S7f, said reaction-productbeing present in an amount 'approximating 0.05 to 0.2% by weight on the weight of the oil. i P

4. Alubricating oil composition consisting'principally of a petroleum lubricating'oil fraction 2,416,807 9 10 5. A lubricating oil composition consisting prin- REFERENCES CITED cipally Of a Petroleum P P on fraction The following references are of record in the and containing in solution in said 011 from about file of this patent: 0.05 to about 1%, by weight, of the reaction prodnot of stearonitrile and P2s5. 5 UNITED STATES PATENTS 6. A lubricating oil composition consisting prin- Number Name Date cipally of a petroleum lubricating oil fraction and 2,347,547 Finley Apr. 25, 1944 containing in solution in said oil from about 2,339,692 Finley Jan. 18, 1944 0.05 to about 1% by weight, of the reaction 2,261,047 Assefi Oct. 28, 1941 product of stearonitrile and P233. 2,242,260 Prutton May 20, 1941 2,141,142 Ralston Dec. 20, 1938 FRANKLIN M. WATKINS. 2,125,851 Ralston Aug. 2, 1938 2,116,472 Ralston May 3, 1938 

